The main objective is to assess if levels of aluminum and tin that are potentially added to food through preparation and storage are sufficient to affect the absorption and utilization of essential elements by human subjects. A second objective is to investigate whether nutritional status in regard to iron, zinc, and copper will affect an animal's sensitivity to tin. Eight adult male subjects will be fed in the first (51 day) metabolic study a basal diet with an additional 0, 50, or 100 mg aluminum, as aluminum hydroxide, daily. Serum aluminum levels and fecal and urinary excretion of phosphorus, calcium, iron, zinc and copper will be monitored. In a rat study the effect of aluminum hydroxide and aluminum phosphate on the apparent absorption and retention of minerals within tissues will be compared. In the second (33 day) metabolic study, eight adult males will be fed a basal diet with an additional 0 or 30 mg tin, as stannous chloride, daily. Serum tin levels and fecal and urinary excretion of iron, zinc and copper, calcium and phosphorus will be monitored. In a series of three rat studies, the effect of varying dietary levels of zinc (5, 12, and 120 microgram/g diet) copper (1, 5, and 50 microgram/g diet) and iron (5, 35, and 350 microngram/g diet) on the retention of tin in tissues will be measured. The effect of tin (0, 200 and 500 microngram/g) on the apparent absorption and retention of zinc, copper and iron will also be determined in these studies.